Nokia sold 4.4 million Lumia smartphones during the fourth quarter of last year, as the company's Devices & Services unit exceeded sales expectations, according to preliminary data.

Nokia currently estimates that Devices & Services net sales in for that quarter was approximately $5.1 billion, with total device volumes of 86.3 million units, the company said on Thursday.

The next 12 months will be key for Nokia and Microsoft, and the sale of 4.4 million Lumia smartphones is a step in the right direction, said Pete Cunningham, an analyst at Canalys.

Nokia also sold 9.3 million Asha touch smartphones, as well as 2.2 million Symbian smartphones.

During the fourth quarter in 2011 Nokia sold 113.5 million units, including around a million Lumia devices and a total of 19.6 million smartphones.

The 4.4 million Lumia smartphones Nokia sold also compares to the 2.9 million it sold during the third quarter. The company could have sold even more if it hadn't been for supply constraints, which especially affected the Lumia 920.

"For example, AT&T and the 920 had significant supply issues with us during the course of the quarter," Nokia CEO Stephen Elop said during a conference call.

But it's difficult to say what could have been were it not for those issues, according to Elop, who is still happy with Nokia's progress.

"We have to make steady progress quarter-on-quarter-on-quarter. Obviously, getting off to a good start with Windows Phone 8 was important in that journey and I think the results today reflect the fact that first step is something we are quite pleased with," Elop said.